Therapeutic Silencing of KRAS Using Systemically Delivered siRNAs

Abstract

Despite being amongst the most common oncogenes in human cancer, to date there are no effective clinical options for inhibiting KRAS activity. We investigated whether systemically delivered KRAS siRNAs have therapeutic potential in KRAS mutated cancer models. We identified KRAS siRNA sequences with notable potency in knocking-down KRAS expression. Using lung and colon adenocarcinoma cell lines, we assessed anti-proliferative effects of KRAS silencing in vitro. For in vivo experiments, we used a nano-liposomal delivery platform, DOPC, for systemic delivery of siRNAs. Various lung and colon cancer models were utilized to determine efficacy of systemic KRAS siRNA based on tumor growth, development of metastasis and down-stream signaling. KRAS siRNA sequences induced >90% knock-down of KRAS expression, significantly reducing viability in mutant cell lines. In the lung cancer model, KRAS siRNA treatment demonstrated significant reductions in primary tumor growth and distant metastatic disease, while the addition of CDDP was not additive. Significant reductions in Ki-67 indices were seen in all treatment groups, while significant increases in caspase-3 activity was only seen in the CDDP treatment groups. In the colon cancer model, KRAS siRNA reduced tumor KRAS and pERK expression. KRAS siRNAs significantly reduced HCP1 subcutaneous tumor growth, as well as outgrowth of liver metastases. Our studies demonstrate a proof-of-concept approach to therapeutic KRAS targeting using nanoparticle delivery of siRNA. This study highlights the potential translational impact of therapeutic RNA interference, which may have broad applications in oncology, especially for traditional “undruggable” targets.

Specific and Efficient Regression of Cancers Harboring KRAS Mutation by Targeted RNA Replacement

“…As in previous reports, which showed that knockdown of KRAS RNA expression with siRNA against the target RNA impeded the growth of human tumor cells harboring the mutant KRAS gene in vivo, 43 reduction of the KRAS G12V RNA expression by the specific ribozymes alone retarded the growth of tumors harboring the mutant KRAS gene in cell cultures as well as in vivo. A slight reduction in the level of wild-type KRAS transcripts (33%-39%) by the ribozyme-encoding adenoviruses was observed in cells harboring wild-type gene, probably due to antisense effects induced by the ribozyme, but it did not affect the growth of cells.…”

RAS isoforms and mutations in cancer at a glance

“…RAF or PI3K effectors) (Fruman and Rommel, 2014;Samatar and Poulikakos, 2014), (iv) inhibitors of processes that support the increased metabolic needs of cancer cells (e.g. macropinocytosis, autophagy, glucose and glutamine metabolism), (v) unbiased genetic or chemical screens for synthetic lethal interactors Kumar et al, 2012;Luo et al, 2009;Sarthy et al, 2007;Scholl et al, 2009) and (vi) RNA interference (RNAi) of KRAS expression (Pecot et al, 2014;Xue et al, 2014;Yuan et al, 2014).…”

KRAS oncogene repression in colon cancer cell lines by G-quadruplex binding indolo[3,2-c]quinolines

“…Other promising approaches are currently being explored, such as RAS-mediated changes in cell metabolism and RAS gene silencing2 by the application of miRNAs or siRNA7. We have previously demonstrated that miR-143 reduces KRAS expression, chemo-sensitizes colon cancer cells to 5-fluorouracil8 and reduces tumour growth in vivo with increased apoptosis and reduced proliferation9.…”